When operating a fluid system in a cold environment or when first starting the engine of the machine, the fluid may be cold and its viscosity very high. Under these conditions if one or more actuators are moved, the volume of fluid flowing through the system may be high. Since the fluid's viscosity is high, it is very difficult to force the fluid through various components of the system, such as the cooler and/or filters. In known systems, attempting to force the fluid through the system has resulted in damage or destruction to some of the system components due to high fluid pressures resulting to resistance to flow. Whenever the fluid temperature of the fluid is below a predetermined level, it is desirable to decrease the fluid flow through the system. Various attempts have been used to offset the above noted problem. One attempt has been to provide a bypass around the cooler or other components whenever the pressure of the return fluid is above a predetermined pressure level. Another attempt has been to reduce the speed of the fan of the cooler responsive to the temperature of the fluid in order to more quickly increase the temperature of the fluid. In other attempts, a bypass valve has been provided to bypass the fluid flow from the pump to the reservoir if the temperature of the fluid is below a predetermined level. The pump's bypassed fluid flow still must be returned to the reservoir through some path and if the volume of fluid is large enough, damage to the cooler, filters, or other components may still occur.
The present invention is directed to overcoming one or more of the problems set forth above.